1. Field of the Invention
This invention relates to techniques for applying a lining material to the inner surface of a pipeline such as a gas conduit, a city water pipeline, a sewer conduit, a conduit in which power cables or communication cables are laid or a petroleum pipeline and particularly an underground pipeline, for the purposes of maintenance, repairs and/or reinforcement.
2. Description of Related Art
Methods of applying a lining material to the inner surfaces of such pipelines or conduits have been used for the purposes of maintenance, repairs and/or reinforcement of various kinds of conduits such as inserting the lining material into a pipeline while the lining material is being turned inside out by the action of fluid pressure, pressing the evaginated surface of the lining material against the inner surface of the pipeline through the action of the above-mentioned fluid pressure, and adhesively bonding the inner surface of the lining material onto the inner surface of the pipeline.
However, in case such a lining method is applied to a pipeline having one or more branched portions to line the inner surface thereof, at the initial stage the lining material is adhesively bonded onto the whole inner surface of the pipeline, and as a result, the openings of the branched pipes formed in the main pipeline also become covered by the lining material, i.e., blocked thereby. At the next or second stage, the lining material layer covering the openings of the branched pipelines is removed by boring the same by means of a borer to thereby enable the branched pipes to communicate with the main pipeline. Upon effecting such a lining operation, if at the above-mentioned initial stage the lining material is adhesively a borer at the above-mentioned second stage, this thick solidified adhesive layer has to be removed, and such removal operations are difficult. To avoid such difficulties, upon effecting adhesive bonding of a lining material onto the inner surface of a main pipeline at the initial stage of the lining operation, the openings of branched pipes in branched portions have been covered with sealing materials prior to conducting the lining material bonding operation. Upon boring the portions of the lining material layer covering the openings during the above-mentioned second stage, the above-mentioned sealing material is then removed together with each of the bored-out portions of the lining material.
An apparatus for blocking openings of branched pipes in branched portions with sealing materials in the above-mentioned operation is described in Japanese Laid-Open Patent Application No. SHO 62-16127. This apparatus comprises a base, on which sealing materials or plugs for blocking openings of branched pipes in branched portions of a pipeline are placed, the base being mounted on an operating machine that is movable through the pipeline, in such a manner that it may be rotated about the longitudinal axis of the pipeline and also moved radially within the pipeline.
This apparatus is disadvantageous in that, since it can carry only one piece of sealing material or plug at a time, each time one of the openings of the branched pipes has to be blocked with a plug, the whole apparatus itself needs to be removed from the pipe in order to place thereon a separate plug for use in blocking the next opening.
Stating this disadvantage in more detail, in general, most of the various kinds of conduits and pipelines such as the above-mentioned gas conduits, city water pipelines and sewers, etc. have a plurality of branched pipelines extending therefrom in the regions close to the terminal ends thereof. For example, low pressure pipelines of gas conduits are buried in the ground under city roads to supply city gas through branched pipelines to neighboring houses and buildings. Many branched pipelines extend from a main pipeline at short intervals. Further, this situation applies also to city water pipelines and sewer conduits.
If the apparatus described in the above-mentioned Japanese Laid-Open Patent Application No. SHO 62-16127 is used for a pipeline having a plurality of branched pipes extending therefrom at short intervals between them, each time one of the openings of the branched pipes has to be blocked with a plug, an extremely inefficient operation of removing the apparatus from the pipeline and placing thereon a new plug for blocking the next opening has to be carried out.
The main object of the present invention is to provide a novel apparatus for use in a pipeline having branched pipes which is free from the above-mentioned disadvantages in the prior art apparatus.